Aaron D. Campbell

A widget that displays rotating images from a post’s gallery in the sidebar of 
your site. You just specify the post or page, and it will cycle through all the 
images from the gallery of that post or page. you can have as many of them as 
you want on your site simultaneously. Requires PHP5.
In WordPress 2.6, another plugin of mine has been included into the CORE to 
allow these to be reorder your images to make them display in whatever order you 
prefer. Until then, go get <a href="https://wordpress.org/extend/plugins/reorder-gallery/" rel="ugc">Reorder Gallery</a>!

Gallery Widget Pro

A widget that displays rotating images from a post's gallery in the sidebar of your site. Requires PHP5.

SebastianK

With this Plugin you can set several descriptions for your blog. They change randomized without reloading the page. You will find an example video on the plugin-page at http://www.scriptpara.de/skripte/spdescchanger/

spDescChanger

With this Plugin you can set several descriptions for your blog. They change randomized without reloading the page.

Gallery Widget Pro vs spDescChanger